Electromagnetic tomography is a relatively new technology with enormous potential for use in medical and related industries. Specifically, the technology is becoming prominently mature and practicable for use in internal, non-invasive, real-time imaging of the physiologic properties of tissues and organs, based on tissue dielectric properties differentiation.
Known microwave tomographic imaging utilizes microwave radiation to image an object by detecting the effects the object had on the microwave beam after it has encountered the object. The changes effected in the reflected microwave, due to this encounter, are dependent upon the dielectric permittivity and conductivity properties of the tissues of the object being imaged. Specifically, for a given microwave frequency, the observed changes in the reflected microwave echo signify a specific signature of the imaged tissue.
Microwaves are ultra-high to super-high frequency radio waves with very short wavelengths ranging from approximately 130 centimeters down to fractions of a millimeter. Frequencies range between 0.1 Giga Hertz (GHZ) to 3000 GHZ. The microwave range which is currently used for microwave imaging of biological tissues is in the range of about 0.5 to about 3 GHZ. However, other ranges of the microwave spectrum may also be used as well. The determinant in the selection of the range is that the radiation be non-ionizing to prevent destruction of tissue members or cells. Accordingly, there are biophysical parameters which should be considered when determining a compatible frequency range.
The prior art utilizes two basic categories of microwave imaging. The first category is static imaging based on forming images by determining the absolute permittivity values of the microwave radiation after its interaction with the object. The second category is dynamic imaging which is based on variations in permittivity within the object occurring at the time of incidence of the microwave radiation. The latter form of imaging is extremely useful in applications in imaging biological tissues to monitor ongoing physiological change. Both static and dynamic imaging techniques require an active imaging process whereby a microwave scanner employs moving or scanning incident radiation and detects the changes in the microwave radiation based on interaction with the object being imaged.
Using dynamic imaging, image reconstruction is based on the difference in diffracted fields recorded from several data sets taken from a body with a changing dielectric contrast. However, internal imaging within larger bodies poses resolution problems which limit the application and scope of dynamic imaging. The present invention provides significant advances over the prior art by integrating biophysical, computer software and microwave tomography technologies to provide a high resolution image.